<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            background-color: #f4ff7d;
        }
        
        .box>div{
            width: 200px;
            height: 200px;
        }

        .d1{
            background-color: #ff5b5b;
        }
        .d2{
            background-color: #66ff66;
        }
        .d3{
            background-color: #7a5fff;
        }

        .box1{
            width: 400px;
            height: 400px;
            background-color: #ff78fd;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="d1">d1</div>
        <div class="d2">d2</div>
        <div class="d3">d3</div>
    </div>
    <div class="box1">
    </div>
</body>
</html>